Rechargeable Zn-based aqueous batteries can be an alternative to Lithium-ion batteries with cheaper anode material; higher scalability; and the use of safer, non-flammable electrolyte. Different from the solid-to-solid reaction mechanism in Lithium-ion batteries, a solid-dissolve-solid mechanism from Zn to zincate ion to ZnO in Zn-based cells introduces two problems. First, dissolution causes Zn deposition to happen in random locations, which leads to electrode morphology change and dendrite growth. Second, ZnO, an insulator, passivates the surface of unreacted Zn, which leads to low utilization of active material and low rechargeability. We have designed an ion-sieving carbon nanoshell coating for ZnO nanoparticles with a two-step scalable procedure. This coating slows down ZnO dissolution but allows hydroxide ions to pass freely, solving the dissolution and passivation problems simultaneously. The nanoshell also prevents dendrite growth and morphology change at the anode. Carbon-coated ZnO nanoparticles outperform uncoated ZnO nanoparticles and Zn foil (with approximately 1.6 times and 6 times longer cycle life, respectively) in a coin cell paired with a NiOOH cathode at a rate of 1C. The unique nanoshell design demonstrates enhanced battery performance and gives insights to direct future analysis and strategies for Zn rechargeable batteries.

Ion-sieving carbon nanoshell for rechargeable Zn-based aqueous batteries

256th National Meeting (2018)

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